Cannot connect using username@zoho.com via mail client

Cannot connect using username@zoho.com via mail client

I have set up an email account using username@zoho.com and can sign in to Zoho webmail using these credentials. However, when trying to connect via an email client (mail on iPad and Outlook 365 for Mac) I get an "Unable to sign in. Check your credentials and try again" error on the MacBook and an authentication error on the iPad indicating that the credentials used to sign on to webmail are being rejected when used in the mail clients. Any suggestions?